Here is my project directory where I have
style.css
under Content and
image.jpg
under Images
Login.aspx page is default page.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Login.aspx.cs" Inherits="LoginDemo.Login" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<link href="~/Content/style.css" rel="stylesheet" type="text/css" media="screen" runat="server" />
<title>LOGIN</title>
</head>
<body>
</body>
</html>
And here is CSS
*{
margin:0px;
padding:0px;
}
body{
background-image:url(Images/image.jpg);
background-size:cover;
background-attachment:fixed;
font-family:Times New Roman ;
}
Page is loaded successfully but without loading background image. Please help me. I read different article and as per suggested solutions I do the same steps but still there is problem.

runat="server"? usually that attribute implies some server side execution/processing and in the stylesheet it looks unnecesary (problematic since there is no handler configured in IIS for css extension).